The present invention relates generally to a cable tie tool having a variable trigger linkage, and more specifically, to such a trigger linkage which may provide different tensioning forces to the tool head of the cable tie tool.
Cable ties are used to bundle or secure a group of articles such as electrical wires or cables. Cable ties of conventional construction include a cable tie head and an elongate strap extending therefrom. The strap is wrapped around a bundle of articles and thereafter inserted through a passage in the head. The head of the cable tie typically supports a locking element which extends into the head passage allowing the strap to be inserted through the passage but preventing retraction of the strap through the passage in the head. Two longitudinally separated portions of the strap are thereby secured to the head to define a loop for holding together the group of articles.
In use, the installer manually places the tie about the articles to be bundled, inserts the strap through the head passage and then manually tightens the tie about the bundle. Further tightening of the cable tie, which increases the tension in the strap thereof, may be provided by a cable tie tool.
One type of such a cable tie tool includes a handle which is generally pistol-shaped and has a barrel into which the strap may be inserted for application of the tension thereto. The handle has a grip which depends from the barrel. The tool includes a trigger mechanism a portion of which is supported within a trigger housing located under the barrel and in front of the grip. The trigger housing is elongate and in generally depending relation relative to the barrel such that, when the heel of the hand of a user is placed against the grip such that the fingers of the hand of the user extend forwardly, the fingers may encircle the forward surface of the trigger housing. Forcibly drawing the fingers toward the heel of the hand, such as by squeezing the trigger housing and grip, causes the trigger housing to be displaced toward the grip. The trigger mechanism is also supported within the barrel and is able to grasp the strap, and to apply the tension thereto in proportion to the drawing or squeezing force applied to the trigger housing.
The ratio of the tension force applied to the cable tie to the drawing or squeezing force applied to the trigger housing is frequently constant and determined by the trigger mechanism. As a result, if an increased tension force is to be applied to the cable tie, a correspondingly larger drawing or squeezing force is required to be applied to the trigger housing.
The application of larger tension forces to a cable tie is frequently required as a cable tie is tensioned because the cable tie normally resists further tensioning after having been subjected to previous tension, particularly if such previous tension is substantial. This, in turn, frequently requires the application of increased drawing or squeezing forces to the trigger housing which are normally provided by the hand of the user. If the required drawing or squeezing forces become sufficiently large, the hand of the user may encounter difficulty in providing such forces.